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1.
Sequential digestions of Fe-Mn oxide coated boulders collected upstream and downstream from the Magruder mine, Lincoln Co., Georgia, indicate probable partitioning relationships for Zn, Cu, Pb, Co, and Ni with respect to Mn and Fe. Initial digestion with 0.1M hydroxylamine hydrochloride (Hxl) in 0.01M HNO3 selectively dissolyes Mn oxides, whereas subsequent digestion with 1:4 HCl dissolves remaining Fe oxides.The results indicate that partitioning is not constant, but varies systematically with respect to the location of metal-rich waters derived from sulfide mineralization. Upstream from the mineralized zone Zn and Ni are distinctly partitioned to the Fe oxide component and Co and Cu are partitioned to the Mn oxide component. Immediately downstream from the mineralized zone, Mn oxides become relatively more enriched in Zn, whereas Fe oxides are relatively more enriched in Cu, Co, and Ni. Analytical precision for Pb is poor, but available data suggests it is more closely associated with Fe oxides.For routine geochemical surveys utilizing coated surfaces, a one-step digestion method is probably adequate. Parameters useful for detecting sulfide mineralization are metal concentrations normalized to surface area or various ratios (e.g. Zn/(Mn + Fe), Cu/Mn, Pb/Fe). Ratios can be obtained much faster, and at lower analytical costs than conventional analysis of stream sediment.  相似文献   

2.
Laser ablation of the Fe and Mn oxide coatings on stream sediments has been tested as a means of rapidly introducing this highly sorptive geochemical exploration medium into an inductively coupled plasma emission spectrometer (ICP) for simultaneous multielement analysis.Training data were obtained by selectively leaching coatings on about ten 1-cm diameter pebbles from 50 sites in the Allen drainage system, Southwest England. The Pb, Zn, Fe and Mn concentrations of the resulting leachates were determined by atomic absorption spectrophotometry. This procedure is relatively rapid and economical, but the leachate is suitable only for the determination of a restricted range of elements (mainly heavy metals). The laser-microprobe testing data were obtained by vaporizing approximately 1 μg of coating from one pebble from each sample site with a laser pulse, producing a crater in the coating 150–200 μm in diameter and 30–50 μm deep. The ablation was effected within a cell which the laser beam penetrates via a quartz window and the vaporized material quickly condenses into an aerosol which is carried in a flow of argon passing through the cell to the ICP, for simultaneous determination of up to 36 elements.Training and testing data for the elements determined were normalized by ratioing to Fe or Mn following a preliminary statistical inspection of the data to ascertain predominant correlations. In the Allen drainage basin, where a narrow and impersistent galena vein with subordinate sphalerite occupies a north-south-trending fracture, Pb determinations on coatings correlate well with the Fe content of coatings, while Zn correlates with Mn. The Pb/Fe dispersion patterns produced by the training and testing procedures are essentially similar, as are the Zn/Mn patterns from each of the procedures, demonstrating the potential of the novel laser microprobe technique.Anomalous Pb/Fe and Zn/Mn ratios in pebble coatings occur in the vicinity of the mineralized fracture. These compare favourably in terms of anomaly contrast and length of dispersion trains (especially their extension beyond major confluences) with the Pb and Zn anomalies detected by the more conventional analysis of the minus 200 μm fraction of the stream sediment. The low levels of potential pathfinder elements associated with mineralization do not lend themselves readily to determination in leachates derived from pebble coatings. Laser microprobe data, however, revealed a low-order but punctual As/Fe anomaly in a tributary, where this cuts the mineralized vein.  相似文献   

3.
The geochemical dispersion, in an arid environment, of Pb and Zn in stream sediments is examined with respect to size fractions and depth of sampling in a stream draining the Gamsberg Zn orebody.Sampling results indicate that there is a well-developed drainage train for approximately 8 km from the orebody for both Pb and Zn. The length of the drainage train is similar for both the minus 80 and minus 200-mesh size fractions but it is less for the minus 10, plus 40-mesh fraction.Higher metal values were obtained from samples taken from the surface of the stream bed. Metal values are generally lower in samples collected below the surface of the stream bed. The sampling position within the stream channel is not important.Sampling of the magnetite fraction from the stream sediments produced a well-defined Zn train for a distance of 14 km from the orebody. This train is more significant than the train found by normal sediment sampling.  相似文献   

4.
Sediment samples were collected from streambeds in an undisturbed watershed in eastern Quebec (Gaspé Peninsula). Two sampling sites were located on a stream draining an area of known mineralization (Cu, Pb, Zn) and two on a control stream. The sediment samples were separated into 8 distinct size classes in the 850 μm to <1 μm size range by wet sieving, gravity sedimentation or centrifugation. Each sediment subsample was then subjected to a sequential extraction procedure designed to partition the particulate heavy metals into five fractions: (1) exchangeable; (2) specifically adsorbed or bound to carbonates; (3) bound to Fe-Mn oxides; (4) bound to organic matter; (5) residual. The following metals were analyzed in each extract: Cu, Pb, Zn; Fe, Mn.Comparison of samples from the mineralized area with control samples revealed the expected increase in total concentrations for Cu, Pb and Zn. Non-detrital metals were mainly associated with Fe oxides (specifically adsorbed; occluded) and with organic matter or resistant sulfides. For a given sample, variation of trace metal levels in fractions 2 and 3 with grain size reflected changes in the available quantities of the inorganic scavenging phase (FeOx/MnOx); normalization with respect to Fe and Mn content in fraction 3 greatly reduced the apparent dependency on grain size.The results of this study suggest that a single reducing extraction (NH2OH.HCl) could be used advantageously to detect anomalies in routine geochemical surveys. A second leaching step with acidified H2O2 could also be included, as the trace metal concentrations in fraction 4, normalized with respect to organic carbon content, also showed high {anomaly/background} ratios.  相似文献   

5.
Soil samples collected from a depth of 8 cm near open wells were studied. Finer (minus 80-mesh) fractions of soil from the A-horizon contain more Mn and Fe compared to coarser fractions and these elements show higher concentrations in soils around wells with a deeper water-table. Greater weathering due to percolation of larger volumes of water through soil results in thorough decomposition of all the minerals, liberating the elements. During this process iron hydroxides with very little Mn form large fragile fragments. Higher Fe/Mn ratios in the minus 44 plus 60-mesh fractions of these soils are characteristic of deeper, high-yielding wells and have a positive correlation with depth of water table.  相似文献   

6.
A hot hydroxylamine hydrochloride (H-Hxl) extraction in 25% acetic acid is compared with the commonly used oxalic acid extraction as a method of anomaly enhancement for Cu and Zn in samples from two very different metal deposits and climatic environments. Results obtained on minus-80-mesh stream sediments from an area near the Magruder massive sulfide deposit in Lincoln County, Georgia, where the climate is humid subtropical, indicate that H-Hxl enhances the anomaly for Cu by a factor of 2 and for Zn by a factor of 1.5, compared to the oxalic method. Analyses of Fe oxide-coated rock samples from outcrops overlying the North Silver Bell porphyry copper deposit near Tucson, Arizona, where the climate is semi-arid to arid, indicate that both techniques effectively outline the zones of hydrothermal alteration.The H-Hxl extraction can also perform well in high-carbonate or high-clay environments, where other workers have suggested that oxalic acid is not very effective. Therefore, the H-Hxl method is recommended for general exploration use.  相似文献   

7.
A study has been completed of the baseline concentrations of Mo in bottom sediments of the major rivers in Colorado. Three hundred and seventy-nine samples were taken from 14 rivers in the state. The geometric means for the concentration of Mo in the minus 80-mesh fraction of the sediment were found to vary from 1.2 to 14.0 ppm. The geometric mean for each river can be logically grouped according to the presence or absence of mineralization upstream in the drainage basin. This grouping results in three categories according to the extent and type of mineralization in the drainage basin. A grouping on the basis of mineralization accounts for 15% of the total variation in the concentration of Mo in the sediment, suggesting that Mo-rich sediment is transported downstream from mineralized areas and exerts a major influence on the baseline concentration. Multiple samples are required to characterize each river because the withinstream component of variance comprises 54% of the total variance.Bottom sediment (minus 80 mesh) is a sensitive indicator of Mo mineralization; values of molybdenum as low as 2 ppm were considered anomalous for several rivers. A precise analytical procedure permits detection of concentrations of Mo in sediment approximately 2 ppm below the detection limit of the usual potassium pyrosulfate-thiocyanate procedure.  相似文献   

8.
Acid-cleaned ceramic plates placed upstream and downstream from a Cu-Zn-Pb sulfide deposit (Magruder mine) developed a precipitate of Fe-Mn oxides in a 36-day period. Copper and Zn concentrations on the coated surface, normalized to surface area and ratios with Fe and/or Mn, are distinctly anomalous for a distance of 2 km downstream from the mine.The major source of metals in the coatings is interpreted to be groundwater percolating into the stream bed. Anomalous concentrations of Cu and Zn in groundwater from the Magruder mine area, due to oxidation of sulfide minerals, probably accounts for the anomaly identified on the ceramic plates.  相似文献   

9.
Geochemical investigations have shown that the nickel sulphide mineralisation at Kambalda is detectable by sampling and analysing the minus 80-mesh fraction of near-surface soils. Over unmineralised mafic and ultramafic rocks the distribution of Ni in soils accurately reflects bedrock Ni distribution. In the environment of sulphide mineralisation Ni is preferentially concentrated in the coarse fractions of the soils, with a corresponding depletion in the minus 80-mesh fraction. Both Ni and Cu nevertheless display strong anomalies in minus 80-mesh fraction soils in the immediate vicinity of sub-outcropping mineralisation.  相似文献   

10.
A governmental regional drainage survey assessed the mineral potential of Calabria in 1974. The Calabria area of southern Italy is a mineralized region in which Penninic and Austro-Alpine nappes, comprising ophiolites, metasedimentary rocks (phyllites, paragneiss, granulites, amphibolites) and granitic and granodiorite plutons, are overthrusting carbonate Apenninic nappes. Pre-Alpine stratabound and vein-type base-metal sulfide mineralization predominate, tectonically redistributed during the Alpine orogeny.A total of 5518 samples of the original 6999 active stream sediments from an area of 10,000 km2 were analyzed by X-ray fluorescence and atomic absorption for Cu, Pb, Zn, Hg, Fe, Mn, As, W, Mo, Sn, and Be on the minus 180 μm fraction. Follow-up investigation of a 39-km2 area around Bivongi-Ferdinandea using 760 soil samples analyzed for Fe, Mn, Zn, Cu, Pb, K, Mo, and Au, investigated molybdenite and chalcopyrite occurrences associated with granodiorite.A five-factor R-mode factor analysis reflected geological and mineralization features in the reconnaissance data. Factor 1 (Fe-Mn-Cu-Zn) is related to the Fe and Mn distribution in the stream sediments. Factor 2 (Be-Sn) reflects presence of pegmatites within metamorphic and magmatic rocks. Factor 5 (Mo) is essentially a single-element factor. Factor 4 (As-Pb-Zn-Hg-Cu) reflects mineralization. Factor 3 (W-Ba) does not cluster in association with any specific lithological unit. Significant metal associations, recognized from R-mode factor analysis, were used as independent variables and regressed against the original metal concentration of each sample. Residuals of multiple regression analysis, differentiated features representing mineralization from those related either to lithologic or geochemical parameters. New prospecting targets were identified and areas of known mineral occurrences were evident in the distinction of residuals.R-mode factor analysis of data from the follow-up investigation identified three factors. Factor 2 (Mo-K) reflects Mo mineralization and associated hydrothermally altered areas but does not suggest additional target areas.  相似文献   

11.
Iron–manganese oxide coatings form on a wide range of geologic samples where they have the ability to adsorb elements and potentially act as a mineral exploration/environmental monitoring tool. In this study, Fe–Mn oxide coatings on stream pebbles were collected from streams in four study areas located across the province of Newfoundland and Labrador, Canada. The study locations were in areas of former copper mines (Tilt Cove and Betts Cove), carbonate geology (Robinsons River), and a metropolitan area (Rennies River). Collected pebbles underwent a simple sample preparation procedure and were then analyzed for a wide range of elements by LA-ICP-MS after optimization of the operating conditions. Water samples accompanied the pebbles, and these were analyzed for pH, dissolved oxygen, conductivity, and a large selection of elements by ICP-MS. Multivariate statistics, in the form of Principal Component Factor Analysis (PCFA) was performed on both data sets. Graphs of the factor scores from the PCFA produced groupings of the samples that were related to geologic/environmental inputs. The loading of variables in each factor was related to the adsorption of the element either to the MnO2 or Fe2O3 phase with most elements except Cr and Cu displaying preferential adsorption to MnO2. Elemental Fe–Mn oxide coating concentrations were a result of the element's affinity (chalcophile, lithophile, or siderophile), pH of the environment, stream water concentration, and amount of each oxide phase present. Even with these complications, LA-ICP-MS analysis of Fe–Mn oxides was able to identify areas of heavy metal pollution and locate geologic inputs.  相似文献   

12.
A multivariate statistical analysis was carried out with log-transformed values of Cu, Ni, Co, Pb, Zn, Ag, Cr, Mn, Ca, and Sr in several sets of samples collected across the mineralized base metal zone in sheared soda granite, feldspathic schist, and chlorite schist from the central section of Mosaboni Mine of the famous Singhbhum Copper Belt of eastern India. Linear correlation coefficient matrices of two sets of ore samples (>0.5% Cu)—one from levels 18 and 21 and the other from levels 25 and 28—indicate two well-defined and distinct clusters comprising Cu, Ni, Co, Pb, and Zn on one hand and Ca, Sr, and Mn on the other. Varimax-rotatedR-mode factor analysis of two above-noted sample sets, taken along with available geologic information, indicates that over 80% of the variability in data matrices for 9–10 elements can be accounted for by four distinct processes: (a) an early phase of copper mineralization which apparently replaced Mn, Ca, and Sr in the host rock; (b) a silicate-cum-oxide phase of crystallization/recrystallization of host rock; (c) remobilization of sulfide-forming ore elements (Cu, Ni, Co, Pb, and Zn); and (d) a phase of mineralization of Ag which appears to have replaced Cr, Ca and Cu. Process (c) was quantitatively most important. Factor score studies are suggestive of preferred introduction of Ni, Co, Pb, and Zn along central parts of preexisting copper-mineralized zones.  相似文献   

13.
Sensitive multi-element analysis techniques were applied to water samples collected in the vicinity of a small Zn-Pb-Cu sulfide mineralization in the region of Menez-Albot (Finistère, France).The variation of the trace-element content along a local stream shows the presence of the mineralization, mainly through a simultaneous positive anomaly in solution for a group of about 10 elements (e.g. Ni, Cu, Zn, As, Sb) which are connected with this type of mineralization. The anomaly decreases steeply due to the influx of swamp water rich in Fe, Mn and organic matter. The precipitation barrier is reflected in the stream sediment composition. Contamination from fertilizers was observed in some samples.  相似文献   

14.
The nature of gold dispersion in soils and stream sediments associated with a copper-gold-mineralized system in northeastern Thailand has been investigated as a basis for identifying appropriate geochemical exploration techniques for the search for comparable deposits in similar environments.Soils were collected with varying relationships to mineralization as a basis for determining sample representativity, size distribution of gold, variation with soil horizon and possible pathfinder elements. Similarly, stream sediments were collected to estimate sample representativity, size distribution of gold, variation of gold with depth in the stream sediment profile and to compare the relative recoveries of gold in field-panned and laboratory-prepared heavy-mineral concentrates. Samples were analyzed for Au and potential indicator elements by a variety of methods but mostly by instrumental neutron activation analysis.Results indicate the consistent distribution of fine-grained gold in soils which allows Au analysis of relatively small samples from B-horizon soils to be used effectively and reliably to identify the surficial patterns of gold mineralization in the study area. Anomalous patterns of other indicator elements, Co, As, Cu, Sb, W, Pb, Zn, Ag, Fe and Mn, may contribute additional information regarding type of mineralization. This finding indicates the effectiveness of soil surveys in gold exploration, particularly in areas of deep weathering where fresh bedrock exposures are infrequent.Unlike soils, size distributions of gold in stream sediments, as a result of the local flow regime, vary both between sampling sites and at depths within a sampling site. Exploration requires Au analysis of the fine fraction (minus 63 μm) of active stream sediments to reduce the problem of sampling representativity. The presence of coarse-grained gold in the stream channel has drawn attention to the possible benefit of using the conventional field-panning method as a semiquantitative technique for providing immediate results. However, highly erratic distribution of pannable gold on a very local scale together with variable proportions of the total gold recovered in field-panned or heavy-mineral concentrates highlights a potentially serious drawback of the method. Combination of analysis of the minus 63 μm fraction and field panning appears warranted to cover the possible existence of gold of a wide size range in stream sediments.The overall results indicate the utility of geochemical exploration techniques in the search for gold mineralization. However, particular care is necessary in the design and implementation of geochemical techniques to ensure maximum reliability of exploration.  相似文献   

15.
The influence of iron hydroxide/oxide coatings on the recovery of gold was studied using 13 stream sediment samples collected from an area of known gold mineralisation. Magnetic products collected from a Frantz isodynamic separator showed higher gold values than did non-magnetic fractions. An acid-treated magnetic product when run through the isodynamic separator yielded a significant amount of non-magnetic component which, when viewed by binocular microscope, showed the presence of gold grains in both bulk sample and in bromoform-separated heavy mineral concentrate. It is suggested that concentrates are treated with 10% HCl prior to magnetic separation where iron oxide coatings are conspicuous.  相似文献   

16.
Two geochemical stream sediment surveys were conducted in the Belgian Ardennes for Fe, Cu, Pb, Zn, Co, Ni and Mn. The geological setting is of quartzo-pelitic rocks of Early Devonian and Cambro-Ordovician age. One survey covers the Ourthe and Salm valleys, the other the Lesse and Lomme drainage basins. Results of these surveys show the geochemical similarity of the two regions. Anomalies have been ascribed to four factors: human activity, Fe-Mn enrichment, known mineralization and potential mineralization. Mean values of metal concentration and statistical dispersion are identical. This results from similar physico-chemical conditions which induce the same types of surficial metallic association. The stream environment is characterized by two main phases, an oxidizing phase where Fe-Mn oxides trap trace metals, and a reducing phase where organic matter and secondary sulphides are bound with Pb, Zn and Cu. In oxidizing conditions, Cu and Ni show a greater affinity for the Fe-oxides while Zn and especially Co are related to the Mn-oxides. Pb has only a weak relationship with the Fe-Mn oxides but is also associated with the organic matter and the secondary sulphides in the reducing environment. Consequently, one may propose the following scale of mobility: Zn > Ni-Mn > Cu-Co > Pb > Fe.  相似文献   

17.
太湖MS岩芯重金属元素地球化学形态研究   总被引：21，自引：4，他引：17  
采用BCR三步提取法对太湖MS岩芯沉积物中Cu、Fe、Mn、Ni、Pb和Zn等6种重金属元素的化学形态进行了研究.结果表明,有效结合态的Cu、Ni和Pb主要以有机物及硫化物结合态、Fe-Mn氧化物结合态存在,Fe和Zn主要以Fe-Mn氧化物结合态存在,Mn主要以可交换态及碳酸盐结合态存在;Fe-Mn氧化物结合态的Ni、Pb和Zn与可还原态的Mn有较好的正相关关系,有机物及硫化物结合态的Cu、Mn、Ni、Pb和Zn与有机碳含量有较好的正相关关系;重金属形态分布体现了重金属元素地球化学性质的差异,以及重金属形态含量与沉积物理化性质的关系.沉积岩芯重金属元素形态垂向变化规律及次生相富集系数表明,Cu、Mn、Ni、Pb和Zn在沉积岩芯13～4 cm有效结合态含量较稳定,为自然沉积;4～0 cm有效结合态含量明显升高,存在一定程度的人为污染.根据137Cs测年结果判断,沉积岩芯Cu、Mn、Ni、Pb和Zn等重金属污染开始于20世纪70年代末期,主要污染元素及污染历史与太湖流域污染工业类型及经济发展阶段相吻合.  相似文献   

18.
Suspended and equivalent active sediments were collected from streams at 84 sites at the eastern and western sides of a ridge with stratabound Zn mineralization, Rockingham County, Virginia (USA). The purpose was to evaluate the relative effectiveness of suspended and bottom sediment in the geochemical exploration for Mississippi-Valley type Zn ores. The orebody is composed of sphalerite and minor amounts of galena with some chalcopyrite, strikes parallel to the enclosing dolomite beds at N34°E, and cuts vertically across the 30°SE dip. Oxidation of the ore extends to about 100 m in depth.Zinc was effective in detecting the mineralized zone. Zinc in the suspensates provided a denser anomaly system (7 strong and 2 moderate samples) than Zn in the <150 μm size of the bottom sediment, either totally dissolved (4 strong and 1 moderate anomalies) or extracted with cold 3% HCl (5 strong and 3 moderate anomalies). The magnitude of the high values for suspensate Zn was considerably higher than those for the other sample types studied. Suspensate Zn was complemented by 3 strong suspensate Cu anomalies. The suspensate Zn anomaly dispersion was about 850 m, 400 m of which was upstream from the mineralization. Lead was detected only in the cold acid extraction and in combination with Cu and Zn gave an extensive overlapping multielement anomaly string that targeted the ore zone and had a dispersion downstream from the mineralization of more than 1000 m. The Pb anomalies extended about 900 m upstream and 400 m downstream from the ore zone. Together with suspensate Zn, the Pb anomalies suggest a continuation of mineralization upstrike from the known orebody.The major anomaly systems are along the eastern side of the ridge with comparatively few anomalies present in the drainage along the western side. The concentration of anomalies in the eastern drainage and anomaly disposition with respect to known mineralization result from structural control on the hydromorphic dispersion of metals from the orebody.  相似文献   

19.
The Bell Springs deposit is a bulk-tonnage, low-grade gold deposit, formed in a hot-spring environment, that is hosted by middle Miocene weakly peralkaline, high-silica rhyolite ash flows and rheomorphic tuffs. Ore grade mineralization over about 460 × 460 m was controlled by northeast- and northwest-trending structures. Sixty-nine soil samples collected along a traverse across the Bell Springs deposit, screened into six mesh size fractions, +10, −10+35, −35+80, −80+120, −120+200, and −200, were treated by low-detection-limit acid digestion/organic extraction procedures, and analyzed by ICP or graphite furnace techniques for Au, Ag, As, Bi, Cd, Cu, Ga, Hg, Mo, Pb, Sb, Se, Te, Tl, and Zn. Twenty-five stream-sediment samples were collected from a drainage crossing mineralization and from a nearby tributary. Sediment size fractions of −200 mesh and −10+200 mesh were analyzed by the same procedures used for soils. In addition, analyses of bulk leachable gold via cyanide leach method (BLEG) was done on bulk −10 mesh sediments.Anomalous Au, Ag, As, Sb, and Mo in all soil size fractions revealed the underlying ore. Areas with anomalous Sb and As were about three times larger than areas with anomalous Au and Ag. Analyses of fine-fractions of stream sediments provided the best-defined Au anomalies in drainages. A multi-element factor calculated by multiplying Au, As, Sb, and Mo reinforced anomalous Au in drainages and correlated well with Bell Springs mineralization.  相似文献   

20.
The distribution of trace metals in active stream sediments from the mineralized Lom Basin has been evaluated. Fifty-five bottom sediments were collected and the mineralogical composition of six pulverized samples determined by XRD. The fine fraction (<?150 µm) was subjected to total digestion (HClO4?+?HF?+?HCl) and analyzed for trace metals using a combination of ICP-MS and AAS analytical methods. Results show that the mineralogy of stream sediments is dominated by quartz (39–86%), phyllosilicates (0–45%) and feldspars (0–27%). Mean concentrations of the analyzed metals are low (e.g. As?=?99.40 µg/kg, Zn?=?573.24 µg/kg, V?=?963.14 µg/kg and Cr?=?763.93 µg/kg). Iron and Mn have significant average concentrations of 28.325 and 442 mg/kg, respectively. Background and threshold values of the trace metals were computed statistically to determine geochemical anomalies of geologic or anthropogenic origin, particularly mining activity. Factor analysis, applied on normalized data, identified three associations: Ni–Cr–V–Co–As–Se–pH, Cu–Zn–Hg–Pb–Cd–Sc and Fe–Mn. The first association is controlled by source geology and the neutral pH, the second by sulphide mineralization and the last by chemical weathering of ferromagnesian minerals. Spatial analysis reveals similar distribution trends for Co–Cr–V–Ni and Cu–Zn–Pb–Sc reflecting the lithology and sulphide mineralization in the basin. Relatively high levels of As were concordant with reported gold occurrences in the area while Fe and Mn distribution are consistent with their source from the Fe-bearing metamorphic rocks. These findings provide baseline geochemical values for common and parallel geological domains in the eastern region of Cameroon. Although this study shows that the stream sediments are not polluted, the evaluation of metal composition in environmental samples from abandoned and active mine sites for comparison and environmental health risk assessment is highly recommended.  相似文献   

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